Baculites ("walking stick rock") is an extinct genus of cephalopods with a nearly straight shell, included in the heteromorph ammonites. The genus, which lived worldwide throughout most of the Late Cretaceous, was named by Lamarck in 1799.
The adult shell of Baculites is generally straight and may be either smooth or with sinuous striae or ribbing that typically slant dorso-ventrally forward. The aperture likewise slopes to the front and has a sinuous margin. The venter is narrowly rounded to acute while the dorsum is more broad. The juvenile shell, found at the apex, is coiled in one or two whorls and described as minute, about a centimeter in diameter. Adult Baculites ranged in size from about seven centimeters (Baculites larsoni) up to two meters in length.
As with other ammonites, the shell consisted of a series of camerae, or chambers, that were connected to the animal by a narrow tube called a siphuncle by which gas content and thereby buoyancy could be regulated in the same manner as Nautilus does today. The chambers are separated by walls called septa. The line where each septum meets the outer shell is called the suture or suture line. Like other true ammonites, Baculites have intricate suture patterns on their shells that can be used to identify different species.
One notable feature about Baculites is that the males may have been a third to a half the size of the females and may have had much lighter ribbing on the surface of the shell.
The shell morphology of Baculites with slanted striations or ribbing, similarly slanted aperture, and more narrowly rounded to acute keel-like venter points to its having had a horizontal orientation in life as an adult. This same type of cross section is found in much earlier nautiloids such as Bassleroceras and Clitendoceras from the Ordovician period, which can be shown to have had a horizontal orientation. In spite of this, some researchers have concluded that Baculites lived in a vertical orientation, head hanging straight down, since lacking an apical counterweight, movement was largely restricted to that direction. More recent research, notably by Gerd Westermann, has reaffirmed that at least some Baculites species in fact lived in a more or less horizontal orientation.
From shell isotope studies, it is thought that Baculites inhabited the middle part of the water column, not too close to either the bottom or surface of the ocean. In some rock deposits Baculites are common, and they are thought to have lived in great shoals. However, they are not known to occur so densely as to be rock-forming, as do certain other extinct, straight-shelled cephalopods (e.g., orthocerid nautiloids).
Baculites fossils are very brittle and almost always break. They are most commonly found broken in half or several pieces, usually along suture lines. Individual chambers found this way are sometimes referred to as "stone buffaloes" (due to their shapes), though the Native-American attribution typically given as part of the story behind the name is likely apocryphal.
Baculites and related Cretaceous straight ammonite cephalopods are often confused with the superficially similar orthocerid nautiloid cephalopods. Both are long and tubular in form, and both are common items for sale in rock shops (often under each other's names). Both lineages evidently evolved the tubular form independently, and at different times in earth history. The orthocerid nautiloids lived much earlier (common during the Paleozoic Era and extinct by the end of the Triassic Period) than Baculites (Late Cretaceous Period only). The two types of fossils can be distinguished by many features, most obvious among which is the suture line: it is simple in orthocerid nautiloids and intricately folded in Baculites and related ammonoids.
Studies on exceptionally preserved specimens have revealed a radula by synchrotron imagery. The results suggest that Baculites fed on pelagic zooplankton (as suggested by remains of a larval gastropod and a pelagic isopod inside the mouth).
Temporal range: Upper Cretaceous
|Baculites fossils from South Dakota. Some|
still have traces of the original nacre (shells).
The type species, Baculites vertebralis is from the upper Maastrichtian, Upper Cretaceous, and is one of the last of its kind.
The lower part of the Campanian stage (Upper Cretaceous) in the Western Interior of North America has yielded Baculites gilberti, early B. perplexus, B. asperiformis, B. maclearni, and B. obtusus, followed temporally by late Baculites perplexus and then by Baculites scotti. The upper part of the upper Campanian has yieled, from older to younger, B.compressus, B coneatus, B. reesidei. B. jenseni, and B. ellasi, followed sequentially in the lower Maastrictian by Baculites baculus, B. grandis, and B. clinolobatis.
Baculites gracilis is known from the Cenomanian Britton Fm., Eagle Ford group of Texas; Baculites ovatus from the eastern U.S. and Baculites pacificum from the Campanian of Vancouver Island, British Columbia.
Species known from Europe, in addition to Baculites vertebratis include Baculites undulatus from the upper Touronian, Baculites leopoliensis from the Upper Campanian and Baculites anceps from the Upper Maastrictian.
The Baculites Limestone is a geologic formation in France. It preserves fossils dating back to the Cretaceous period.Baculitidae
Baculitidae is a family of extinct ammonoid cephalopods that lived mostly during the Late Cretaceous, and often included in the suborder Ancyloceratina.Baculitid genera are characterized by a small to minute initial coil of about two whorls followed by a long straight or slightly curved shaft. Genera are distinguished on the basis of size, general shape, particulars of the suture, and ornamentation. They can reach lengths of 120 cm (47 in) or more.Baculitids are found worldwide in deposits from the upper Albian to the Maastrichtian ages. Related families are the Anisoceratidae, Diplomoceratidae, Hamitidae, Nostoceratidae, and Turrilitidae; all of which along with the Baculitidae are included in the superfamily Turrilitoidea.Genera included in the family include:
TuberosciponocerasCalcaires à Baculites
The Calcaires à Baculites is a geologic formation in France. It preserves fossils dating back to the Cretaceous period.Fresvillia
Fresvillia is an extinct cephalopod genus belonging to baculitid family of the ammonoid order Ancyloceratida that lived during the Late Cretaceous, found in France. Baculitids are a kind of heteromorph ammonite characterized by a straight adult shaft, often preceded by a small coiled juvenile portion.
Baculites, Boehmoceras, Eubaculites, and Lechites, are among related genera.List of the Mesozoic life of Arkansas
This list of the Mesozoic life of Arkansas contains the various prehistoric life-forms whose fossilized remains have been reported from within the US state of Arkansas and are between 252.17 and 66 million years of age.List of the Mesozoic life of Colorado
This list of the Mesozoic life of Colorado contains the various prehistoric life-forms whose fossilized remains have been reported from within the US state of Colorado and are between 252.17 and 66 million years of age.List of the Mesozoic life of Delaware
This list of the Mesozoic life of Delaware contains the various prehistoric life-forms whose fossilized remains have been reported from within the US state of Delaware and are between 252.17 and 66 million years of age.List of the Mesozoic life of Kansas
This list of the Mesozoic life of Kansas contains the various prehistoric life-forms whose fossilized remains have been reported from within the US state of Kansas and are between 252.17 and 66 million years of age.List of the Mesozoic life of Wyoming
This list of the Mesozoic life of Wyoming contains the various prehistoric life-forms whose fossilized remains have been reported from within the US state of Wyoming and are between 252.17 and 66 million years of age.List of the prehistoric life of Arkansas
This list of the prehistoric life of Arkansas contains the various prehistoric life-forms whose fossilized remains have been reported from within the US state of Arkansas.List of the prehistoric life of Colorado
This list of the prehistoric life of Colorado contains the various prehistoric life-forms whose fossilized remains have been reported from within the US state of Colorado.List of the prehistoric life of Delaware
This list of the prehistoric life of Delaware contains the various prehistoric life-forms whose fossilized remains have been reported from within the US state of Delaware.List of the prehistoric life of Mississippi
This list of the prehistoric life of Mississippi contains the various prehistoric life-forms whose fossilized remains have been reported from within the US state of Mississippi.List of the prehistoric life of New Mexico
This list of the prehistoric life of New Mexico contains the various prehistoric life-forms whose fossilized remains have been reported from within the US state of New Mexico.List of the prehistoric life of South Dakota
This list of the prehistoric life of South Dakota contains the various prehistoric life-forms whose fossilized remains have been reported from within the US state of South Dakota.List of the prehistoric life of Wyoming
This list of the prehistoric life of Wyoming contains the various prehistoric life-forms whose fossilized remains have been reported from within the US state of Wyoming.Orthoceras
Orthoceras ("straight horn") is a genus of extinct nautiloid cephalopod restricted to Middle Ordovician-aged marine limestones of the Baltic States and Sweden. This genus is sometimes called Orthoceratites. Note it is sometimes misspelled as Orthocera, Orthocerus or Orthoceros (Sweet 1964:K222).
Orthoceras was formerly thought to have had a worldwide distribution due to the genus' use as a wastebasket taxon for numerous species of conical-shelled nautiloids throughout the Paleozoic and Triassic. Now, Orthoceras sensu stricto refers to O. regulare, of Ordovician-aged Baltic Sea limestones of Sweden and neighboring areas.These are slender, elongate shells with the middle of the body chamber transversely constricted, and a subcentral orthochoanitic siphuncle. The surface is ornamented by a network of fine lirae (Sweet 1964:K224). Many other very similar species are included under the genus Michelinoceras.Paleontology in South Dakota
Paleontology in South Dakota refers to paleontological research occurring within or conducted by people from the U.S. state of South Dakota. South Dakota is an excellent source of fossils as finds have been widespread throughout the state. During the early Paleozoic era South Dakota was submerged by a shallow sea that would come to be home to creatures like brachiopods, cephalopods, corals, and ostracoderms. Local sea levels rose and fall during the Carboniferous and the sea left completely during the Permian. During the Triassic, the state became a coastal plain, but by the Jurassic it was under a sea where ammonites lived. Cretaceous South Dakota was also covered by a sea that was home to mosasaurs. The sea remained in place after the start of the Cenozoic before giving way to a terrestrial mammal fauna including the camel Poebrotherium, three-toed horses, rhinoceroses, saber teeth, and titanotheres. During the Ice Age glaciers entered the state, which was home to mammoths and mastodons. Local Native Americans interpreted fossils as the remains of the water monster Unktehi and used bits of Baculites shells in magic rituals to summon buffalo herds. Local fossils came to the attention of formally trained scientists with the Lewis and Clark expedition. The Cretaceous horned dinosaur Triceratops horridus is the South Dakota state fossil.Williams Fork Formation
The Williams Fork Formation is a Campanian (Edmontonian) geologic formation of the Mesaverde Group in Colorado. Dinosaur remains are among the fossils, most notably Pentaceratops sternbergii, that have been recovered from the formation, although none have yet been referred to a specific genus. Other fossils found in the formation are ammonites, Neosuchia, and the mammal Meniscoessus collomensis.